Audio interfaces may make human interaction with machines possible through a voice/speech platform in order to initiate an automated service or process. Voice interfaces have become more commonplace, and people are taking advantage of the value that these hands free and eyes free interfaces provide in many situations. Compared with visual interfaces, however, voice interfaces have the restriction that it is generally difficult to present multiple items of spoken information at the same time. Automated voice answering systems for phones are a typical example. A conceivable approach for improving the efficiency of a voice interface is to substantially simultaneously present multiple items of spoken information to a user. With this approach, however, one item of spoken information is masked by another item of spoken information due to psychoacoustic effects, which make it difficult for the user to recognize what is spoken.